Low drift, highly accurate pressure sensors are required for measuring the pressure on drilling tools used to drill deep into the earth. These pressure measurements are referred to as “down-hole pressure measurements”. The stability of the pressure sensors for deep well tools in high-temperature, high-pressure, down-hole applications is critical. Deep wells typically have a 20,000 psi background pressure. Pressure differences of 1 or 2 psi (i.e., pressure differences that are 0.01% of the background pressure) between two strata locations can indicate the presence of oil bearing strata. An unstable pressure sensor unit would prevent detection of oil bearing strata in an oil drilling application.
Since drill diameters/pipe diameters of less than 4 inches outer-diameter are required for deep wells, deep well tools require small diameter pressure sensors. Current down-hole, high-temperature, high-pressure devices require a barrier diaphragm between the sensing device and the media being sensed; this barrier diaphragm increases the size of the sensor.